Stellar Clusters in the 4MOST footprint - Sara Lucatello Antonella Vallenari INAF OAPd
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Stellar Clusters in the 4MOST
footprint
Sara Lucatello
Antonella Vallenari
INAF OAPd
Team
• Al Momany, Y. (IT) • Dalessandro, E. (IT)
• Lucatello, S. (IT)
• Alfaro , E. (ES) • Damiani, F. (IT) • Mapelli, M. (IT)
• Alves, J. (AT) • De Silva, G. (AU) • Meingast, S. (AT)
• Baumgart, H. (AU) • Flaccomio, E. (IT) • Micela, G. (IT)
• Bonito, R (IT) • Gieles M (ES) • Miglio, A. (UK)
• Bossini, D. (PT) • Gratton, R. (IT) • Prisinzano, L. (IT)
• Bragaglia, A. (IT) • Guarcello, M. (IT)
• Salaris, M. (UK)
• Campbell, S (AU) • Jeffries, R. (UK)
• Schiavon, R. (UK)
• Cantat-Gaudin (ES) • Jordi, C. (ES)
• Tautvasiene, G. (LT)
• Carrera, R (IT) • Larsen, S. (NL)
• Vallenari, A (IT)
• Carretta, E (IT) • Lattanzio, J. (AU)
• D’Orazi, V (IT)
Globular Clusters
[O/Fe] Carretta+ 2009 Milone+ 2016
• Variations of C-N, Na-O, Mg-Al, F, Li,
in some cases even Fe and n-capture
• GCs must have contributed to the
formation of the Halo (~2% halo
stars have chemical signature typical
of SG GC stars) and perhaps also the
Bulge (see Schiavon+ 2016).
Koch+2019
Still open issues
• How do they form and evolve?
– Where (and when) does the second generation form?
– What is the production site(s) of the polluters?
– Where does the “diluting gas” come from?
– How do binaries affect their evolution?
– Do stars in the different population evolve differently?
• What is their relationship with their environment?
– Is the formation of the multiple population related to the environment
(e.g. distance from the Galaxic center/disk at birth etc)?
– Is (are) the second generation(s) modulated by the environment or
other global cluster properties?
• How do they contribute to the build up of the halo (and Bulge)?
– Are stars from different populations lost to the environment at the
same rate?
– What is the role of internal dynamics and binaries?
Clusters in 4MOST
• Wide field is key!
• Gaia gives indication on
membership
• 4MOST data yield:
– Uniformely derived
parameters, metallicity, FLAMES
and alphas HST
– Uniformely derived WFC3
abundances of key
elements (Na, Al, Mg, n-
capture)
– Radial velocities (can also
estimate the binary 4MOST
Image: M5 ESO
fraction)
Sample size and distribution
~120 GC in the 4MOST footprint
10000
7500
~20K stars G< 18 ~160 stars/GC
GC potential targets ~5K with G < 15.5 ~40 stars/GC
Proposed targets
N
5000
In terms of stars:
>3 times the largest sample to
2500
0
date for HR
10 12 14
Gmag
16 18 > 5 for LR
0
In terms of clusters:
> 5 number of clusters
−20
Unlikely to change: 4MOST is
best survey instrument to do
DEC
−40
that.
−60
−80
5 10 15 20
RA
Clusters and validation Clusters are ideal targets for validating the pipelines and provide calibration and cross- calibration with other surveys.
Ocs in the MW
• Their birth, internal kinematics/ dynamical evolution, evaporation, disruption,
self-pollution (if any) trace the Galactic environment
à Tidal field (Berentzen & Athanassoula 2011, Kupper et al 2010)
à interaction with giant molecular clouds & spiral arms
(Gieles et al 2006, Kujissen+2011) + stellar evolution effects (infant mortality)
G1,
• The older OCs trace the Mucciarelli+201
kinematics/structure of the disk 7
• Tracing the spiral structure
ü (Carraro+2017, Moitinho + 2010,
Dias&Lepine2005, Molina-Lera+2017 , Jacobson+2016
Minchev2015, Chiappini+ )
• Clusters age , metallicity,
positions, orbits should be
compared with field star
properties, to trace the disk
chemical gradient à disk
formation and evolution process
( Minchev+2015, Jacobson+2016,
Bragaglia+ 2006, Cantat+2016) Anders 2017
Open questions
• Can we put further constraints on stellar physics to safely use stars as fossils for
the Galactic formation and evolution? à Age> 100 Myr
• mixing, rotation
• How do clusters dynamically evolve to populate the MW field? à all age Ocs
• chemical tagging of young/old clusters in the field
• Kinematic identification of lost stars in the field
• How OCs trace the structure (disk, warp…)?
• How OCs trace the kinematics and dynamics of the disks? à old Ocs (age >500 Myr)
• What is the shape of abundance gradients and their time evolution in the MW ?
• Diagnostic
• Kinematics: membership, distances, orbit reconstruction
• chemical information, completeness
• Ages and time evolution of the system à disk properties
OC Present Status
• About 3000 Ocs (Kharchenko+2013, Cantat+2018, 2019, )
• Distances and membership for 1200 Ocs (Cantat-Gaudin, Jordi, Vallenari+ 2018)
• 84% of Ocs have uncertainty4MOST OC Survey
All spectral types
AFGK stars
1500 Ocs visible from South
Selection criteria: log(Age) > 7.0 ; low Av à780 Ocs
HR: About 270,000 stars with G< 15.5à 48,000 AFGKà 60 stars/OC
LR: About 400,000 stars with G< 18 à 107,000 AFGK à 137 stars/OCPreliminary target distribution
All sample
AFGK stars G< 18
G< 15.5Target selection
absG
DEC
DEC
G
b G
BP-RP l
• Criteria: selecting on wide areas to detect escaping stars
• High priority on known members -àusing Gaia dataWEAVE-4MOST synergy
• OCS WEAVE Survey
• (PI: A.Vallenari)
• About 100 targets
• Large field: Disruption of
open clusters
– chemical tagging of young
clusters in the field
• OCs as tracers of the
Galactic disc and of its
chemical evolution
• Complementing APOGEE&
GES(Frinchaboy+2013,
Carrera+2019, Magrini+2017)
à Science case/target
selection revision based
on new Gaia DR2+ data
Feltzing 2018OC & GC Requirements
• HR: Stellar parameters and individual abundances in all main nucleosynthetic
channels to G=15.5, i.e. closely matching the Gaia’s most precise sphere
(distances, ages) with abundances at 0.1 dex
• Teff, log(g), Vrad, Vsini, [Fe/H]
• At least a few elements for each nucleosynthetic chanels :
• Light elements (Li, C,N) à young/intermediate age objects
• p-capture elements (Na, Al)
• iron peak (Fe, Sc, Ni, Cr, Co, Zn),
• alpha elements (C, Mg, Si, Ca, O, Ti…),
• neutron-capture slow and rapid elements (Zr, Y, Sr, Ba, La, Nd,Eu),
• LR: accurate Vr (2 km/s) (and stellar parameters, incl. Metallicity at 0.2
dex) GConclusions • Understanding of the formation of the Galactic components cannot be complete w/o the study of stellar clusters • GC survey would allow to explore for the first time their outskirts gaining crucial insight in the phenomenon of the multiple populations and their formation • OC survey complementing disk • Total of ~1600 clusters (120 GCs and 1500 OC) and ~175K stars (55K HR and 120K LR) • On target fibre-hours ~0.2M-0.3M ~1% of total 4MOST time • Survey would also amount to a rather complete calibration and validation sample, which include several overlap clusters with other past, ongoing and planned surveys (SEGUE, APOGEE, GES, GALAH, WEAVE etc)
You can also read
